1. Field of the Invention
This invention relates to fluid fittings.
2. Description of the Prior Art
Swaged fittings for joining tubular members together, such as in a hydraulic system or for connecting tubular members to other devices, have been used very successfully because they are reliable, easy to service, such as by making connections in the field, and are relatively low in cost. The integrity of the joint and life of the connection is very favorable compared with other types of fittings for connecting tubular elements.
In one such device, as shown in U.S. Pat. No. Re. 28,457, the fitting includes exterior redges which, upon swaging, are transferred to the inner surface of the fitting. In other words, the inner surface of the fitting initially is of constant diameter except for small sealing grooves, while the exterior surface is provided with ridges. After the swaging operation, the exterior surface is of constant diameter and the ridges are transferred to the inner surface of the fitting to provide a connection with the tube.
This type of fitting relies upon the springback of the tube in obtaining a strong connection between the fitting and the tube. This limits the utility of the fitting because some tubular members are made of low-yield strength materials, such as copper, copper-nickel, some aluminums, some titaniums, and the like, and do not exhibit appreciable springback upon compression. Tubular conduits of this type are used extensively in the hydraulic systems of ships. These tubular members are of relatively great wall thickness which renders it impractical to attempt to transmit the contour of the exterior of the fitting to the interior to so deform the tubular element upon a swaging operation. Also, the creation of the ridges on the inner surface of the fitting, and hence on the inner surface of the tubular member in the fitting, would result in constrictions which may produce undesirable pressure drops. Also, such ridges on the interior of the fittings create noise as the hydraulic fluid is conducted through the system which may not be acceptable in the construction of submarines where silent operation is essential.